Atmospheric Remote Sensing: Instruments

Tunable Optical Profiler for Aerosol and oZone (TOPAZ) lidar

TOPAZ lidar instrument
TOPAZ lidar installed on a Twin Otter aircraft

We designed and built the Tunable Optical Profiler for Aerosol and oZone lidar (TOPAZ) instrument. TOPAZ incorporates state-of-the-art technologies to make it compact and lightweight as well as having low power consumption. These features allow it to be deployed on smaller aircraft. Its wavelength flexibility permits optimization for differing atmospheric conditions including interference from other atmospheric components and allows dual-DIAL operation – introduction to Differential Absorption Lidar (DIAL) techniques.

This lidar was first deployed in the Texas Air Quality Study (TexAQS) 2006 field campaign to help examine pollution development and transport in the vicinity of Houston, Texas. During the experiment, TOPAZ proved to be a useful tool for the study of urban air quality by its ability to provide detailed coverage over a wide area for the mapping of ozone and aerosol plumes from an airborne platform. Additional information obtained from the lidar data included boundary height determination and ozone plume flux measurements.

TOPAZ is also part of the NASA Tropospheric Ozone Lidar Network (TOLNet) - ground-based profiling of tropospheric ozone. More recently TOPAZ has been used to measure the ozone distribution along the Front Range of Colorado, and other areas of the western United States. The lidar was installed in a box truck, and this mobile unit deployed to take ozone measurements aloft.

Contact: Christoph Senff, Raul Alvarez

Basic Parameters Measured

  • Ozone concentration profiles
  • Aerosol backscatter
TOPAZ example data
Ozone cross sections show the impact of complex terrain on local flow patterns and ozone distribution in the Denver/Boulder Front Range Urban Corridor.
TOPAZ lidar instrument
TOPAZ lidar mobile unit

Typical Specifications

Tuning range285-310 nm (three wavelengths)
Pulse energy0.2-0.8 mJ/pulse
Pulse rate1 kHz with pulse-to-pulse tuning capability
(333 Hz for each individual wavelength)
LaserDiode-pumped Nd:YLF laser quadrupled in LBO (intracavity) and CLBO (external) to 262 nm to pump Ce:LiCAF in a tunable cavity
Minimum range0.3 km
Maximum range4 km
Eye-safe range150 m
System weight800 lbs (including chiller and control electronics)
Dimensions30" x 56" x 45" laser/optics frame, 15" x 25" x 24" chiller
Electronics in standard 19" equipment racks ~49" (28U)
System power3 kW, 110VAC
DigitizerFPGA-based digitizer (14 bits, 100MHz sample rate)
OutputReal-time ozone and aerosol profiles displayed in flight.
Data is recorded to a solid state disk drive.
Vertical/horizontal resolution90 m / 600 m (10 s at a flight speed of 60 m/s)
Accuracy±3 - ±15 ppbv (depends on range and ozone concentration)
TOPAZ 3D rendering
TOPAZ schematic
TOPAZ 3D rendering and Schematic of lidar optical design.

Field Projects

Project NameDateLocation
COVID-AQSCOVID Air Quality Study202003Spring 2020Boulder, Colorado (ground site)
FAST-LVOSFires, Asian, and Stratospheric Transport - Las Vegas Ozone Study201705May - June 2017Las Vegas, Nevada (ground site)
SCOOP 2016Southern California Ozone Observation Project 2016201608August 2016southern California (ground site)
CABOTS 2016California Baseline Ozone Transport Study 2016201605June - August 2016Visalia, California (ground site)
DISCOVER-AQ 2014DISCOVER-AQ 2014201407July-August 2014Erie, Colorado (ground site)
DISCOVER-AQ 2013DISCOVER-AQ 2013201309September 2013Houston, Texas (ground site)
LVOS 2013Las Vegas Ozone Study 2013201305May - June 2013Angel Peak, Nevada (ground site)
UBWOS 2013Uintah Basin Winter Ozone Study 2013201301January - February 2013Horsepool, Utah (ground site)
UBWOS 2012Uintah Basin Winter Ozone Study 2012201202February 2012Horsepool, Utah (ground site)
CalNexCalifornia Research at the Nexus of Air Quality and Climate Change 2010201005May - July 2010Southern California (Twin Otter, aircraft based)
TexAQS 2006Texas Air Quality Study 2006200007July - September 2006Houston, Texas (Twin Otter, aircraft based)